Cohort studyindependent cross-checkabstract checked I-LEG-129 standard review
Soy formula and reproductive organs at age 5
Compared with feeding infants breast milk or cow-milk formula, soy formula feeding does not affect subsequent reproductive organ size at 5 years of age.
Overview
Andres A et al.. J Nutr 2015 · PMID 25761499 · DOI 10.3945/jn.114.206201
Children fed soy formula had reproductive organs of the same size and structure as breastfed or cow-milk-fed children.
Does the study support the specific claim? No · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Check reproductive organs after soy formula.
- How was the study done?
Cohort with ultrasound.
- How many people, animals or samples were studied?
101 children.
- What was actually found?
No differences.
- How large was the observed effect?
Not significant.
- What do the results mean in everyday life?
No visible hormonal effect at age 5.
- What are the study's limitations?
Small.
- What does it say about Elawady's specific claim?
Limits C-LEG-10.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
It cannot exclude later effects.
Scientific in-depth review
1. Full reference
- Authors
- Andres A et al.
- Journal
- J Nutr
- Year
- 2015
- Identifier
- PMID 25761499 DOI 10.3945/jn.114.206201
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref works API
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Not stated in abstract.
2. Research question
Does soy formula feeding alter reproductive organ size and structure at age 5?
3. Study design and population
- Study design
- Cohort study – Prospective cohort (Beginnings study) with ultrasonography at age 5
- Population
101 children (50 boys, 51 girls)
- Country
Not stated in abstract (Beginnings study)
- Period
Follow-up at 5 y
- Sample size
101 (35 breastfed, 32 cow-milk formula, 34 soy formula)
- Inclusion and exclusion criteria
Beginnings cohort participants.
4. Methods and endpoints
- Exposure / intervention
Soy formula in infancy
- Comparator
Breast milk; cow-milk formula
- Endpoints
Breast bud, uterus, ovaries, prostate, testes volumes and structure
- Statistical methods
Adjusted for race, gestational age, birth weight
5. Actual results
- Results
No significant differences between diet groups in any reproductive organ volume or structural characteristic in girls or boys.
- Absolute risks
Not applicable
- Authors' conclusion
No early infant feeding effects on reproductive organs at age 5; follow-up through puberty planned.
6. Strengths
- Prospective; objective imaging
7. Weaknesses
- Small; early age
- Abstract only
8. Risk of bias
- Orienting tool
- ROBINS-E
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Non-randomised feeding groups.
9. Assessment of the statistical interpretation
Underpowered to exclude small effects.
10. Relevance to the specific claim
Does not find hormonally driven organ changes after soy formula (limits C-LEG-10).
11. Independent contrary findings
I-LEG-130 (menstrual pain), A-LEG-09.
12. Transferability to Germany and Europe
Applicable.
13. Overall methodological judgement
Reassuring but small.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | low |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Pubertal outcomes.
15. Linked fact checks
- Soy phyto-oestrogens reach hormonally concerning levels in infants fed soy formula (6-11 fold the hormonally active adult dose; plasma isoflavones 13,000-22,000 times oestradiol). – Studies contradicting or limiting the claim